All posts in Food Allergy and Intolerance

A new study has suggested that allergies may be linked to pesticides found in tap water.

Researchers at the American College of Allergy, Asthma and Immunology used existing government data to see whether people with more dichlorophenols in their urine were more likely to have food allergies. Dichlorophenols are a kind of chlorine in certain pesticides that are known to kill bacteria, and in theory, they could be killing the naturally occurring bacteria in humans’ digestive systems, causing food allergies.

“We wanted to see if there was an association between certain pesticides and food allergies, and we were specifically interested in dichlorophenols because those were the ones that had this antibacterial effect,” said lead researcher Dr. Elina Jerschow. “When researchers have compared bacteria from the bowel in healthy kids versus bacteria in the bowel for kids that have lot of allergies, they’ve noticed a big difference.”

The number of children and teens with food or digestive allergies in the United States has increased 18 percent between 1997 and 2007, according to a 2008 study by the Centers for Disease Control and Prevention. That’s about 3 million people under 18 years old.

Eggs, fish, milk, peanuts, shellfish, soy, tree nuts, and wheat make up 90 percent of food allergies, according to the CDC report. Symptoms can range from mouth tingling to anaphylaxis, which is the swelling of the throat and tongue and can lead to death.

Jerschow clarified that the researchers were only looking for a statistical association, meaning they were not able to examine patients to see how these chemicals physically caused their allergies. Because it’s only an association, these findings could mean that the chemicals caused the food allergies, or it could mean the food allergies caused the chemicals in the urine. That part is not yet clear.

“While the study does not allow concluding that pesticides are responsible for the allergies, it certainly raises the possibility and justifies pursuing the kinds of studies that can help sort of if these pesticides are, indeed, the cause,” said Dr. Kenneth Spaeth, who directs the Occupational and Environmental Medicine Center at North Shore University Hospital. He was not a researcher involved in the study.

Spaeth said the study findings fit in with a growing evidence that pesticide exposure can damage the immune system, which could increase allergies as well.

Researchers were surprised to find that dichlorophenol levels in urine didn’t vary between urban and rural areas, Jerschow said. They concluded that even those who opted for bottled water instead of tap water could ingest the pesticide chemical from eating fruit, fruit juices and foods with cocoa powder, like chocolate.

As such, Jerschow said the research is still too preliminary to suggest that people should change their eating or drinking habits.

Children who are allergic to food are found to be suffering from anxiety and are increasingly more lonely; One allergic child out of five never attends peers’ parties, while one in four always brings along “safe” food. The burden of food allergies and the risk they can escalate to life-threatening diseases is particularly heavy on children, whose normally active and sociable lifestyle can be severely limited and frustrated by the effort to keep them away from potentially dangerous food.

According to a study presented at the 2011 Food Allergy and Anaphylaxis Meeting by the European Academy of Allergy and Clinical Immunology (EAACI), held Feb 17-19 in Venice, Italy, 23 percent of allergic children are no longer curious to try new food to vary their diet, considered too monotonous by most of them. A child out of ten also gives up crucial physical activity for fear of anaphylactic shock triggered by exercise.

“About 17 percent of allergic children, regardless of their age, never go to a party or a picnic with friends, while 24 percent are forced to bring along something to eat,” says Prof. Maria Antonella Muraro, Chair of the EAACI Meeting. The study, headed by Prof. Muraro, was carried out by the Center for the study and treatment of allergies and food intolerances at the hospital of the University of Padua, Italy on 107 young patients and their mothers.

“Also, 5 to 15 per cent of cases of anaphylactic shock can be triggered by physical activity following the consumption of small amounts of allergenic food that would otherwise be harmless, so one allergic child out of ten also stops every kind of exercise,” Prof. Muraro added. “Allergies are often downplayed as a minor problem, but the life of an allergic person can be hell. Allergic children show to be more afraid of being sick and a higher level of anxiety about food than children with diabetes. The constant alarm surrounding them is taking a toll on their development and well-being.”

Another worrisome problem adding to the poor quality of life of allergic patients, especially the younger ones, is the need to carry life-saving devices at all times, such as epinephrine auto-injectors, “loaded” with enough drug to prevent death in case of severe anaphylactic shock. They are easy to use, light to carry and discreet, but one out of three patients still leaves home without them.

“Within 8 or 10 minutes the shot reverses the symptoms, ranging from urticaria to respiratory distress, cardiovascular collapse and gastrointestinal problems including vomiting and diarrhoea,” explains Prof. Muraro. “It can cause minor side effects, such as irritability or tremors that end as soon as the adrenaline is processed by the body, generally within a couple of hours. Patients should not be scared, even those who have a heart disease: the possible side effects are negligible in comparison to the opportunity to save your life.”

There is no scientific evidence that complementary therapies or kits sold through websites can identify allergies, the UK NHS watchdog NICE says. It says sites for services such as hair analysis use plausible stories but are not backed up by scientific evidence. It is publishing new guidance to help doctors in England and Wales identify when a child may have allergy problems. NICE says some parents end up turning to alternative therapies after a perceived lack of help from their GPs.

It is estimated that one in 20 young children has a food allergy. Dr Adam Fox, an allergy specialist based at the Evelina Children's Hospital in London, says not all children suffer immediate and obvious symptoms. “Food allergies can actually be extremely subtle. Lots of children have eczema, colic or spit up more food than usual. For some of those children the underlying problem is an allergy to something within their diet.”

The guidelines include detailed advice about how to recognise symptoms and when to refer to specialists. Dr Fox, who helped write the guidelines for National Institute for Health and Clinical Excellence (NICE), says he often sees parents in his specialist clinic who have wasted money on complementary or alternative tests.

The review by NICE looked for any scientific research of the usefulness of approaches including hair analysis and Vega testing, which uses mild electric currents, or kinesiology, in diagnosing allergies in children. “The websites are very well put together, the stories behind them are plausible, but we were unable to find any evidence to support them,” says Dr Fox. He says there are two types of testing used in NHS clinics – skin prick and blood sample – which are backed by scientific research. NICE is warning that parents sometimes turn to alternative tests when they have failed to convince their family doctor to listen to their concerns.

It took Alison Berthelson more than two years to get an allergy diagnosis for her first son Harris. She had been to the local surgery several times when he suffered rashes and stomach upsets without any particular cause being identified. After Harris ate a small piece of chocolate containing nuts he suffered a more extreme reaction, becoming agitated, with an extreme rash covering his entire body. The out-of-hours GP gave her son a medicine to reduce swelling, but did not send him on to hospital as an emergency. “It was really very terrifying, terrifying at the time because we didn't know what was happening, and terrifying later when we did know what had happened and how lucky we were.” A new GP correctly diagnosed possible food allergies, and sent Harris for testing at a specialist NHS clinic. He now has to avoid nuts, sesame and some other ingredients used in prepared foods.

Allergies on rise The number of children suffering from food allergies appears to be increasing, although experts are at a loss to understand exactly why. Family doctors are now more likely to see very young children suffering allergic reactions. Dr Joanne Walsh, a GP involved in drafting the advice, says she now sees several children a week with suspected allergic reactions. Some are babies just a couple of weeks old. By gradually eliminating, and reintroducing different foods, she can help parents manage the allergy without the need for hospital visits. “There's nothing more rewarding than a parent coming back and saying it's like having a different child.”

Researchers have a new theory on why some kids get unexplained tummy aches.

In some people, the small intestine is unable to efficiently break down fructose (and sometimes other forms of sugar). This problem is sometimes referred to as fructose intolerance. The undigested fructose passes into the large intestine, where it is broken down by bacteria. A by-product of this process is the creation of carbon dioxide and hydrogen. These two gases build up in the intestine, causing bloating, gas, pain and diarrhea. In some cases, the problem can affect absorption of important nutrients, like calcium and iron.

Researchers estimate about 33 percent of Americans have some level of sensitivity to sugar, most commonly to fructose, but the symptoms are often vague. Some people with fructose intolerance can eat small amounts of the sugar and not have any problems, making diagnosis even trickier.

Daniel Lustig, M.D., Pediatric Gastroenterologist at Mary Bridge Children’s Health Center in Tacoma, WA, says patients with chronic digestive problems should have a physician’s evaluation to rule out other possible causes of the symptoms, like Celiac disease or Crohn’s disease. Once those conditions have been ruled out, he recommends a diagnostic tool called the breath hydrogen test.

A patient is given a dose of fructose. Then, periodically, he/she breathes into an air collection bag. The gases from the bag are retrieved and analyzed for the presence of hydrogen (one of the gases given off when fructose is broken down in the large intestine). Patients whose hydrogen levels exceed 20 points beyond a baseline reading are likely to be fructose intolerant.

Lustig explains the main treatment of fructose intolerance is avoidance of foods containing fructose. That includes fruits, fruit juices, sodas and processed foods and drinks with high fructose corn syrup. Since fructose is in so many foods, it can be tricky to find and hard to avoid.

Lustig recently performed a study to look at possible fructose intolerance in 245 children and adolescents (ages 2 to 18) with unexplained chronic abdominal pain, gas or bloating. The breath hydrogen test found that nearly 54 percent of the participants tested positive for fructose intolerance. Lustig says the problem appeared to be especially high among teen girls.

Those who were judged to be fructose intolerant were given advice on using a low-fructose diet. The investigators found that nearly 68 percent of those who followed the recommended diet had an improvement or resolution in their symptoms.

In the past, positive blood and skin tests would often be mistaken for a food allergy because they would indicate the presence of immunoglobulin E antibodies, but it is important to remember that these are typically higher in patients with atopic dermatitis, according to a speaker at the 69th Annual American Academy of Dermatology Meeting conducted in New Orleans this week. “Those antibodies are not diagnostic, and the only way to diagnose food allergy is with a strong history of reactions or a challenge,” Jon M. Hanifin, MD, of Oregon Health & Science University, said in a press release. “This is done in a doctor’s office, using small increments of the food in question and increasing the amount until an allergic reaction occurs or does not occur. Usually a parent can pinpoint if a child has a true food allergy because the allergic reaction will appear so quickly with lip swelling or hives, quite distinct from simply food intolerance.”

Between 6% and 10% of children have atopic dermatitis, and about one-third of these children have food allergy. Recent research examining the genetic basis of atopic dermatitis has shown that this chronic skin condition is likely related to a defect in the epidermal barrier, which allows irritants, microbes and allergens (such as food) to penetrate the skin and cause adverse reactions. Because the skin barrier in patients with atopic dermatitis is compromised and open to absorb proteins, it allows sensitization to certain foods, leading to a positive skin or blood test.

New guidelines recently issued by the National Institute of Allergy and Infectious Diseases established a protocol for the proper evaluation and management of food allergy. The guidelines recommend that children who are younger than aged 5 years with moderate to severe atopic dermatitis be considered for food allergy evaluation if they have persistent atopic dermatitis despite optimized management or if the child has a reliable history of an immediate reaction after eating a specific food.

Hanifin said research is also ongoing into whether withholding foods is leading to more allergies than an unrestricted diet in young children. This may provide future insight in potential ways to prevent food allergies. He said children in Israel seldom get peanut allergy, which may potentially be attributed to the use of peanut proteins in pacifiers in that country. In the United States and Europe, where peanut allergies are more common, infants are not usually exposed to this food until they are toddlers – the time when most peanut allergies are noticed.

“There is some thinking that withholding foods might actually be causing more allergies, and that an unrestricted diet may help tolerize babies to foods that could potentially cause a problem later in life,” Hanifin said. “Ongoing studies in this country using oral immunotherapy appear promising, and physicians hope that we may discover how to prevent food allergies in the future while continuing to provide successful treatment for children with atopic dermatitis.”

Eating more fruits and vegetables may not protect children from developing allergies, according to a large Swedish study that questions earlier hints of benefit. Fruits and vegetables are rich in antioxidants, which are thought to reduce airway inflammation. So recent studies reporting less asthma, wheezing and hay fever among children who consumed more produce appeared to make sense.

But not all research has found that link, and the studies that did may have had a surprising flaw, said Helen Rosenlund of Karolinska Institutet in Stockholm, who led the new study. She said some proteins in fruits like apples and pears resemble the pollen parts that trigger hay fever, meaning that kids might react to both. In other words, existing allergies may have caused them to eat around the produce, rather than the other way around. “This could confuse research findings,” explained Rosenlund, “falsely suggesting that diets with fewer fruits and vegetables result in more allergic disease.”

To find out if this was the case, Rosenlund and her colleagues looked at data on nearly 2,500 eight-year-olds who had participated since birth in a larger Swedish study. Based on blood tests and questionnaires filled out by parents, the researchers found that seven percent of the children had asthma. The rates of hay fever and skin rashes were more than twice as high. The average child ate between one and two servings of fruit, and between two and three servings of vegetables each day.

At first glance, some produce did seem helpful: Kids with the biggest appetite for fruit had less than two-thirds the odds of developing hay fever than those who ate the least amount. Apples, pears and carrots appeared to be particularly helpful, the researchers report in the Journal of Allergy and Clinical Immunology, but there was no such link for vegetables overall. However, it turned out that half the children with hay fever were sensitive to birch tree pollen, one of the pollens known to resemble the proteins in apples and carrots. And sure enough, after the team repeated their analysis excluding the 122 kids with food-related allergy symptoms, the hay fever link disappeared as well. “Fruits do not seem to offer protection against allergic if diet modifications are considered,” say Rosenlund.

The researchers say more studies are needed, particularly in other parts of the world that may have a different variety of allergy triggers, or allergens. And they advise those studies should not forget to look at how allergies might influence what participants eat. “Studying diet it is not so easy when it comes to the relation with allergic disease,” Rosenlund said, “because it is such a complex disease pattern.”

SOURCE: bit.ly/g3DpI7 The Journal of Allergy and Clinical Immunology, online January 10, 2011.

A controversial new Dutch study may have found a link between food allergies and ADHD. However, many experts are dismissing the findings. The study found that in children with ADHD, putting them on a restrictive diet to eliminate possible, previously unknown food allergies or sensitivities decreased hyperactivity for 64% of them. “There is a longstanding, somewhat inconsistent story about diet and ADHD,” said Jan Buitelaar, the lead author of the Dutch study and a psychiatrist at the Radboud University Nijmegen Medical Centre. “On the one hand, people think it’s sugar that’s the trigger, others think that food coloring could be causing ADHD. Our approach was quite different. We went [with] the idea that food may give some kind of allergic or hyperactivity reaction to the brain.”

There have been previous studies in this field, but they were limited. “This has long been viewed as a kind of a controversial approach,” Buitelaar said. “When we started the research, I was skeptical, but the results convinced me.”

In the study, of the 41 kids who completed the elimination diet, 32 saw decreased symptoms. When certain foods thought to be “triggers” for each child were reintroduced, most of the children relapsed. Among 50 kids given a “control” diet that was just a standard, healthy diet for children, no significant changes were noted. Given these findings, Buitelaar recommended that the elimination diet become part of standard of care for children with ADHD. However, while pediatricians acknowledge some effectiveness, they were against the elimination diet as part of the care for children with ADHD.

“People seem to think that dietary modification is essentially ‘free,’ but it is difficult, socially disruptive, and presents the risk for nutritional deficiency,” said Dr. Michael Daines, a pediatric allergist-immunologist at the University of Arizona. Though Daines is willing to work with families who want to try an elimination diet for treating ADHD, he feels it will only have an effect if the child is having a true food allergy or intolerance.

A lack of testing for food allergies is putting children's health at risk and could lead to life threatening reactions, a study has found. The study, Adverse reactions to food in New Zealand children age 0-5 years, was published in the New Zealand Medical Journal. It looked at a cross-section of 110 children who had attended Plunket clinics. It found 44 had experienced an adverse reaction to food, but only four had been clinically evaluated. Those children were found to have adverse reactions to food allergens, including a life threatening peanut allergy. Two others had been hospitalised with systemic symptoms, but neither had undergone testing for food allergy. “If these children have food allergies, they remain at risk for continued and possibly severe reactions,” the study said.

Parents modifying children's diets or breastfeeding mothers cutting out food without advice from a physician or dietician could also have adverse affects, it said. “Failure to thrive is commonly seen in children experiencing FA (food allergy) as a result of multiple foods being removed from their diet.” The data indicated adverse reactions to food were a public health concern and may be under investigated — even when symptoms were severe, the study said.

“There is an urgent need to investigate the epidemiology, diagnosis, and prevention of FA (food allergy) in New Zealand to reduce morbidity, improve child health, and reduce the burden to health costs.” Thirty-three of the children were reported to have eczema. Ten had worsening symptoms two hours after eating, the study said. Symptoms improved in six of them with dietary changes. Doctors had prescribed topical therapy for 18 of those children with eczema, but symptoms had persisted.

“One possible explanation for this observation is undiagnosed FA (food allergy). Without testing, allergic triggers for eczema could not be identified in these participants.” Further investigation of food allergy as the cause of eczema was warranted, the study said.

Adverse reactions to food worldwide in children was an increasing concern and food allergy was as common in New Zealand as in other countries, the study said. The study was conducted by the Auckland District Health Board and led by Associate Professor Rohan Ameratunga and lead researcher Dr Christine Crooks. Allergy New Zealand chief executive Penny Jorgensen said the study was “really disturbing” because it highlighted that many children were not being assessed for food allergy. The risk was the potential for life-threatening reactions, she said.

A coordinating committee representing 34 professional organizations, advocacy groups and federal agencies oversaw the development of the guidelines. The coordinating committee selected a 25-member expert panel, chaired by Joshua Boyce, M.D., co-director of the Inflammation and Allergic Disease Research Section at Boston's Brigham and Women's Hospital. The panel used an independent, systematic literature review of food allergy and their own expert clinical opinions to prepare draft guidelines. Public comments were invited and considered as well during the development of the guidelines.

“These guidelines are an important starting point toward a goal of a more cogent, evidence-based approach to the diagnosis and management of food allergy,” says Dr. Boyce. “We believe that they provide healthcare professionals with a clear-cut definition of what constitutes a food allergy and a logical framework for the appropriate use of diagnostic testing and accurate interpretation of the results.”

Additional topics covered by the guidelines include the prevalence of food allergy, natural history of food allergy and closely associated diseases, and management of acute allergic reactions to food, including anaphylaxis, a severe whole-body reaction. They also identify gaps about what is known about food allergy.

“The food allergy guidelines provide a rigorous assessment of the state of the science, and clearly identify the areas where evidence is lacking and where research needs to be pursued,” says Daniel Rotrosen, M.D., director of the Division of Allergy, Immunology and Transplantation at NIAID. “This information will help shape our research agenda for the near future.”

Food allergy has become a serious health concern in the United States. Recent studies estimate that food allergy affects nearly 5 percent of children younger than 5 years old and 4 percent of teens and adults. Its prevalence appears to be on the rise. Not only can food allergy be associated with immediate and sometimes life-threatening consequences, it also can affect an individual's health, nutrition, development and quality of life. While several potential treatments appear promising, currently no treatments for food allergy exist and avoidance of the food is the only way to prevent complications of the disease.

Food allergies, by some accounts, affect about 4 percent of adults and 5 percent of children under the age of 6 in the United States, though this study raises questions about the reliability of such figures.

Food allergies can cause a variety of problems, ranging from mild skin rashes or nausea to a life-threatening, whole-body reaction known as anaphylaxis. The allergies can also have serious effects on patients' social interactions, school and work attendance, family economics and overall quality of life. “It's a life-defining diagnosis in a way,” said Chafen.

The National Institute of Allergy and Infectious Diseases is working on new clinical practice guidelines and, as part of its efforts, enlisted Chafen and her colleagues to review the current evidence on food allergies.

The researchers started their work by sifting through thousands of scientific papers, published between 1988 and 2009, that focused on the four foods — milk, eggs, fish and peanut and tree nuts — responsible for more than half of all allergies. They ultimately reviewed 72 studies, including one meta-analysis on prevalence, 18 studies on diagnosis, 28 studies on management, and four meta-analyses and 21 additional studies on prevention.

When examining the literature, the researchers found there was no universal definition of “food allergy,” in spite of NIAID's defining it as an “adverse immune response” that is “distinct from other adverse responses” such as a food intolerance. In fact, 82 percent of the studies provided their own definition of food allergy.

“This validates the idea that there exists a great deal of complexity and confusion in the field of food allergy, even at the level of the medical literature,” said co-author Marc Riedl, MD, MS, section head of clinical immunology and allergy at UCLA.

Along the same lines, there was a lack of uniformity for criteria in making a diagnosis. The current gold standard is the food challenge, during which a physician gives a patient a sample of the suspected offending food, sometimes in capsule form, and then monitors for allergic reaction. However, this test requires specialized personnel, is expensive and has a risk of anaphylaxis. Office-based tests were used to diagnose many patients; these include a skin-prick test, during which a dilute extract of the potential allergen is placed on the skin, and a blood test that determines the presence of food-specific allergic antibodies known as IgE.

As the researchers discuss in their paper, the concern with the latter two tests is that they're not definitive: Patients with non-specific symptoms, such as a rash or digestive troubles, and positive skin-prick or blood tests actually have less than a 50 percent chance of having a food allergy. In order to make a proper diagnosis, they pointed out, physicians need to evaluate the data within the context of a patient's history and have a great understanding of symptoms consistent with true food allergy.

What this means, then, is there is a potential for the overdiagnosis of food allergy.

“I frequently see patients in my clinical practice who have food intolerance, but have previously had inadequate or inappropriate evaluation and been told they have a 'food allergy',” said Riedl. “This causes a great deal of unnecessary anxiety and concern for the patient.”

Previous studies have tried to determine whether the skin-prick or blood test is superior over the other, but in reviewing the evidence, Chafen and her colleagues found “no statistical superiority in either test.” They also found generally inconclusive results from 10 previous studies in which the tests were combined, in an effort to improve diagnostic accuracy.

“I was very surprised,” said Chafen. “I'm a general internist and I thought diagnostic strategies were more-studied.”

In terms of treatment, Chafen said expert opinion is that an elimination diet — having the patient stop consuming the food that causes the allergic reaction — is the most common. Although the approach is a common-sense one (“If a patient breaks out in hives repeatedly after drinking milk, it's your instinct as a physician to say, 'Don't drink milk,'” Chafen said), the researchers found the treatment hasn't been well-studied.

It would be unethical to conduct controlled studies of elimination diets for patients with serious, life-threatening allergic reactions, but as pointed out in the paper, there are few studies of this approach on patients with relatively minor symptoms.

“In these instances, the benefits of an elimination diet are uncertain based on published evidence and potential benefits need to be weighed against the potential nutritional risks of such a diet, particularly in children,” the researchers wrote.

Chafen and her colleagues also found that immunotherapy, a treatment in which the body's immune system is altered by administering increasing doses of the allergen over time, appeared to be effective at eliminating symptoms in the short term. Immunotherapy isn't a licensed method for allergy treatment, but the researchers urged more study on its long-term effect and safety.

In all, the researchers concluded, the food-allergy field is in need of uniformity in the criteria for what constitutes an allergy and a set of evidence-based guidelines upon which to make this diagnosis. NIAID, which put together an expert panel and has reviewed the group's analysis, is planning to finalize such guidelines later this summer.

As for Chafen, who sees patients with potential food allergies, these findings have encouraged her to rely more on specialists to help clinch a diagnosis. “People need to be seen by someone with a deep understanding of diagnostic tests and criteria,” she said. “The distinction between food intolerance and food allergy is really important.”

The study was funded by NIAID. Other Stanford authors on the study are Dena Bravata, MD, a PCOR affiliate; and Vandana Sundaram, MPH, assistant director of research for CHP/PCOR. Paul Shekelle, MD, PhD, with the RAND Corp.'s Southern California Evidence-Based Practice Center and the West Los Angeles VA Medical Center, is the senior author.